1. Field of the Invention
The present invention relates to a driver load measuring method, device, and program for measuring a load on a driver, and a storage medium for storing the program, and more particularly to a driver load measuring method, device, and program for quantitatively measuring a load on a driver driving a vehicle accompanied by attitude changes, and a storage medium for storing the program.
2. Description of Background Art
As a device for quantitatively measuring a load on a driver, techniques for measuring a load on a driver driving a four-wheeled vehicle by a steering entropy method are disclosed in Japanese Patent Laid-open No. 11-227491 and in Proceedings Nos. 45-99, pp. 5-8, Development of “Steering Entropy Method”, of a corporate juridical party, Science Lecture Meeting.
The steering entropy method is a method of measuring a driver load according to the smoothness of a steering operation (steering angle) as an input from the driver to the vehicle. If the driver attention is distracted by the load, the time of no steering operation becomes longer than that under no load on the driver, so that a large steering angle error is stored and a corrective steering amount to be corrected upon restoring the driver attention becomes large. Thus, smoothness is lost from time-series data of the steering angle. As a result, variations in steering angle error become large to cause an increase in entropy.
In the steering entropy method disclosed in Japanese Patent Laid-open No. 11-227491, attention is focused on the fact that the smoothness of steering operation changes according to the presence/absence or magnitude of a load on a driver. Further, steering angles in a four-wheeled vehicle under the load on the driver are detected as time-series data, and this time-series data is compared with time-series data under no load on the driver to obtain an error therebetween. This error is statistically analyzed to thereby obtain the load.
The course control in a four-wheeled vehicle of the vehicles accompanied by attitude changes depends substantially on only a steering angle. Therefore, the driver load can be detected as a change in steering angle. However, the course control in another type of vehicle, such as a motorcycle, is performed not only by a steering operation, but also by the shift of a passenger's weight or a throttle operation. Accordingly, in a motorcycle or the like, the driver load cannot be detected by the detection of a steering angle as in the prior art.